KIT and medium chain acyl-CoA dehydrogenase deficiency: However, in our patients with severe MCAD the expression intensity ratio for GNNK(–)/(+) (the KIT isoforms characterized by the presence or absence of the tetrapeptide sequence glycine-asparagine-asparagine-lysine (GNNK) in the extracellular part of the juxtamembrane region) was ≥ 95% (Fig. 1; Fig. S1).